Types of Insulation

The attic is often the most cost-effective place to add insulation. Usually, a contractor blows loose fill into and over the top of ceiling joists. For the do-it-yourselfer, batts laid sideways on existing insulation are an easy alternative.

• The air barrier at the ceiling line must be tight to ensure warm moist air from the house does not get into the cold attic and condense in the winter. Check ceiling light fixtures, the tops of interior walls and penetrations such as plumbing stacks for air leakage.
• Ensure that soffit venting is not blocked by added insulation; baffles may have to be installed.

Basement walls are unique because they must handle significant moisture flows from both inside and outside the house. The preferred method, from a building science perspective, is to insulate the wall on the outside with rigid insulation suitable for below-grade installations, such as extruded polystyrene or rigid fibreglass.

Typically, this is a wood-frame wall with the potential for insulation in the stud cavity (batts or spray-applied) and on the exterior face of the studs (rigid insulation).